Microplates, also known as micro-well plates, are a standard product and are regularly used in medical, chemical and biological laboratories. A perspective view of a microplate 1 is shown in FIG. 1A. Microplate 1 has microplate lid 2 and microplate base 4. Microplate 1 shown in FIGS. 1A and 1B has just one well. FIG. 1C shows a microplate with 96 wells in its base 4 and FIG. 1D shows a microplate with 384 wells in its base 4. Microplates with 1536 wells are also available.
In the laboratory, microplates are commonly filled with various media. The media can be either in a liquid form or have a thicker, viscous consistency, such as that found in Agar. It is very important to the efficient productivity of a laboratory to be able to pour media into microplates accurately and rapidly. In order to produce a high volume of prepared microplates, an automated machine can provide the required throughput much faster than a technician can. To this end there are several automated devices that are currently available that will automatically fill microplates with media. Thermo Vision, Inc. with offices in Grand Junction, Colo., makes an automated filling machine that can only handle ten plates at a time and must be monitored continuously to remove filled plates and add new ones. Zymark Corp., with offices in Hopkinton, Mass., produces a liquid handling workstation, but it is also for low capacity runs and requires constant supervision. A automated filling machine is known that has slightly greater capacity than those made by Thermo Vision and Zymark Corp., but the increased capacity is limited on the input side and there is no restacking capability. This means that there has to be a technician present at all times to remove filled plates and make room for the new ones. This machine also uses an expensive robot for positioning. The robot adds extra cost to the device. CCS Packard, with offices in Torrance, Calif., produces a couple of machines that include both an input and an output chamber that can hold up to 50 plates. These devices rely on a conveyor system.
The main problems with the above known devices are that they are very expensive and must be monitored at all times due to low capacity and/or no input/output unstacking and restacking capabilities.
In order to save money, there have been attempts to make manual microplate filling machines. U.S. Pat. No. 5,415,060 discloses a device in which a bridge that aligns and holds steady a hand-held liquid dispenser means is positioned over microplate holder for a manual application of liquid. Although this device may be considerably less expensive than prior art automated devices, it is too slow and impractical for many laboratories.
What is needed is a relatively inexpensive automatic machine with simple mechanisms for rapidly filling a large volume of microplates without constant supervision.